The present invention relates to casement window hinges and in particular to a casement window hinge better resisting pullout, for example, caused by increased window weight.
Casement window hinges allow a window to open by pivoting about a vertical axis that moves inward as the window opens. This combination motion is provided by special casement window hinges that slide along a track supporting the window sash. A separate operator moves the window as mounted on the hinges, typically using a crank mechanism.
Casement window hinges typically employ a two-bar linkage of a sash arm and guide arm. The sash arm is attached along the window sash, for example, by countersunk wood screws directed up through the sash arm into the wood or other material of the sash. An inward end of the sash arm is pivotally attached to a slide or “shoe” that may move along the track attached to the window opening and that defines the movable pivot point or hinge point of the window. A center of the sash arm is pivotally attached to one end of a guide arm. The remaining end of the guide arm is pivotally attached to the track displaced from the slide.
Normally each window is supported by two casement window hinges on corresponding shoes, one positioned at a lower edge of the window and the other positioned at the upper edge of the window, the hinges being generally mirror images of each other. Increased interest in energy conservation has led to the introduction of triple glazed windows providing three layers of glass separated by air gaps. Triple glazed windows have substantially higher weight than so-called double pane windows and can exert substantial outward lateral threes on the casement window shoe leading to premature failure and pullout of the shoe from the track. This can also be true for large windows or windows that have greater weight.